In other words, the amounts of chlorophyll a in the microcosms were not significantly different. After a one-day exposure to paraquat, there was a sharp fall in the amount of chlorophyll a in every microcosm, except A. Microcosms B, C and D, which comprised 1.443, 0.960, and 0.676 mg/m2 of chlorophyll a respectively, significantly surpassed microcosm F containing 0.286 mg/m2 of the same pigment. However, the amount of chlorophyll a in microcosm F was not statistically different from that in microcosm E where the amount of chlorophyll a was at 0.340 mg/m2.